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Hearing Controls (hearing + control)

Distribution by Scientific Domains
Life Sciences50%

Selected Abstracts

3D Mapping of brain differences in native signing congenitally and prelingually deaf subjects

HUMAN BRAIN MAPPING, Issue 7 2010
Natasha Leporé
Abstract In the prelingual and congenital deaf, functional reorganization is known to occur throughout brain regions normally associated with hearing. However, the anatomical correlates of these changes are not yet well understood. Here, we perform the first tensor-based morphometric analysis of voxel-wise volumetric differences in native signing prelingual and congenitally deaf subjects when compared with hearing controls. We obtained T1-weighted scans for 14 native signing prelingual and congenitally deaf subjects and 16 age- and gender-matched controls. We used linear and fluid registration to align each image to a common template. Using the voxel-wise determinant of the Jacobian of the fluid deformation, significant volume increases, of up to 20%, were found in frontal lobe white matter regions including Broca's area, and adjacent regions involved in motor control and language production. A similar analysis was performed on hand-traced corpora callosa. A strong trend for group differences was found in the area of the splenium considered to carry fibers connecting the temporal (and occipital) lobes. These anatomical differences may reflect experience-mediated developmental differences in myelination and cortical maturation associated with prolonged monomodal sensory deprivation. Hum Brain Mapp, 2010. © 2009 Wiley-Liss, Inc. [source]

GJB2 Mutations in Mongolia: Complex Alleles, Low Frequency, and Reduced Fitness of the Deaf

ANNALS OF HUMAN GENETICS, Issue 2 2010
Mustafa Tekin
SUMMARY We screened the GJB2 gene for mutations in 534 (108 multiplex and 426 simplex) probands with non-syndromic sensorineural deafness, who were ascertained through the only residential school for the deaf in Mongolia, and in 217 hearing controls. Twenty different alleles, including four novel changes, were identified. Biallelic GJB2 mutations were found in 4.5% of the deaf probands (8.3% in multiplex, 3.5% in simplex). The most common mutations were c.IVS1 + 1G > A (c.-3201G > A) and c.235delC with allele frequencies of 3.5% and 1.5%, respectively. The c.IVS1 + 1G > A mutation appears to have diverse origins based on associated multiple haplotypes. The p.V27I and p.E114G variants were frequently detected in both deaf probands and hearing controls. The p.E114G variant was always in cis with the p.V27I variant. Although in vitro experiments using Xenopus oocytes have suggested that p.[V27I;E114G] disturbs the gap junction function of Cx26, the equal distribution of this complex allele in both deaf probands and hearing controls makes it a less likely cause of profound congenital deafness. We found a lower frequency of assortative mating (37.5%) and decreased genetic fitness (62%) of the deaf in Mongolia as compared to the western populations, which provides an explanation for lower frequency of GJB2 deafness in Mongolia. [source]

Non-hospital delivery and permanent congenital and early-onset hearing loss in a developing country

BJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 11 2008
BO Olusanya
Objective, The objective of this study was to determine the role of non-hospital delivery and other risk factors for permanent congenital and early-onset hearing loss (PCEHL) in a developing country. Design, Matched case,control study. Setting, Four primary healthcare centres in inner-city Lagos, Nigeria. Population, Fifty-six infants with PCEHL and 280 normal hearing controls matched for age and sex from a population of infants not older than 3 months attending Bacille de Calmette-Guérin immunisation clinics. Methods, Conditional logistic regression analyses of infant and maternal characteristics associated with PCEHL, and the evaluation of population exposure to each risk factor. Main outcome measures, Adjusted matched odds ratios and population attributable risk percent (PAR%). Results, Children with PCEHL were significantly more likely to be first born (OR 1.9, 95% CI 1.1,3.6) without skilled attendants at birth (OR 2.4, 95% CI 1.3,4.5) and have a history of neonatal jaundice requiring exchange blood transfusion (NNJ/EBT) (OR 9.6, 95% CI 2.4,38.2) but less likely to be small for gestational age (SGA) (OR 0.1, 95% CI 0.0,0.5). After controlling for other covariates, the absence of skilled attendants at birth (OR 4.2, 95% CI 2.0,8.6) and NNJ/EBT (OR 19.1, 95% CI 4.3,85.5) emerged as predictors of PCEHL, while SGA (OR 0.1, 95% CI 0.0,0.2) retained its inverse relationship with PCEHL. The PAR% was 35.9% for the lack of skilled attendants at birth and 10.6% for having NNJ/EBT. About 23% of children with PCEHL did not exhibit any risk factors. Conclusions, NNJ/EBT and the absence of skilled attendant at birth rather than the place of delivery are significant predictors of PCEHL in this study population. Targeted hearing screening using these risk factors would facilitate the detection of about 77% of children with PCEHL. [source]

Language and Theory of Mind: A Study of Deaf Children

CHILD DEVELOPMENT, Issue 2 2007
Brenda Schick
Theory-of-mind (ToM) abilities were studied in 176 deaf children aged 3 years 11 months to 8 years 3 months who use either American Sign Language (ASL) or oral English, with hearing parents or deaf parents. A battery of tasks tapping understanding of false belief and knowledge state and language skills, ASL or English, was given to each child. There was a significant delay on ToM tasks in deaf children of hearing parents, who typically demonstrate language delays, regardless of whether they used spoken English or ASL. In contrast, deaf children from deaf families performed identically to same-aged hearing controls (N=42). Both vocabulary and understanding syntactic complements were significant independent predictors of success on verbal and low-verbal ToM tasks. [source]